Gravitation

Gravitation is the interaction associated with energy and momentum, described in general relativity as spacetime curvature and, in Newtonian physics, as a universal attractive force.

General relativity: Einstein’s theory of gravity describes gravitation as the curvature of spacetime produced by energy and momentum. It gives the relativistic account of gravitation stated in the definition.
Spacetime: A four-dimensional framework combining space and time into an interconnected structure. General relativity describes gravitation through the geometry of this framework.
Solar System: The Sun and the objects gravitationally bound to it. Planetary orbits provide precise tests of gravitational theories.
Quantum field theory: A framework combining quantum mechanics with special relativity to describe fields and their particle excitations. It underlies the other fundamental interactions but does not provide a complete quantum theory of gravitation.
Graviton: A hypothetical quantum particle that would mediate gravitational interactions in a particle-based description. No graviton has been detected, and its status reflects gravity's unresolved quantum description.
Newton's law of universal gravitation: A classical law stating that masses attract with a force proportional to their product and inversely proportional to distance squared. It models gravitation as a force rather than spacetime curvature.
Stress–energy tensor: A mathematical object encoding energy density, momentum density, and stresses in relativity. It represents the energy and momentum that source spacetime curvature.
Mercury's perihelion precession: The gradual rotation of Mercury's orbital ellipse, including a relativistic contribution unexplained by Newtonian gravity alone. Its anomalous advance became a classic test of general relativity.
Quantum gravity: A proposed framework for describing gravity with quantum principles. It seeks to reconcile general relativity with quantum physics.
Cosmological constant problem: The mismatch between theoretical estimates of vacuum energy and the observed value driving cosmic acceleration. It exposes a deep tension between quantum fields and gravitation.

Linked from 9 pages